First prints have artifacts: how to improve?

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Hi to all, I'm brand new to the 3D printing and UM community. I just got a UM2 a week ago and been trying to print some things with increasing levels of success. I'm still trying to catch up will all the jargon and how to address it (under extrusion, etc).

I'm trying to make an enclosure for a project and been experiencing a couple issues. The following image is blue Ultimaker PLA printed a 210 deg and 50% speed. It has a 3mm fillet all around which didn't print well. Note that it has been printed with the filet side right on the build plate (no tape or glue) without a raft or brim.

I understand you can't have strong overhangs, but what is going here? I can understand for the corner, since although it's hard to see on the picture, but all corners have peeled a bit so the extruder kept melting the corners over and over. But for the "straight" horizontal parts? Also I can seem to have clean corners on the vertical walls either. Any idea? Also

Another artifact I noticed, is some sort of "echo" in the print next to the right notch (circled). I read from some forums posts it has to do with acceleration? How do you control this parameter in Cura, can't seem to find it (or is it only for UM1)?

In my next test, I made a small version of the previous model, with a 1mm fillet. I used Colorfabb PLA/PHA @ 210deg, 50mm/s speed, .1mm layers and added a brim to avoid curling of the corners. Oh and I upgraded the firmware to the lastest. Still seems to be some issues:

Overall, there was no curling and the outside fillet on the bottom looks good to me (but the vertical ones still is not that smooth like on the first pic). But we can see the interior floor could not bind well to the infill and left holes. I got that on several other test prints. What could help on this? Another issue is that "bulge" that appears from the beginning of the notch and for a few layers. How do you call this? Anybody has tips on this?

Finally, from the bottom, we can see gaps (top part)...is that what's call under extrusion? And is the overall line pattern and distance seems good to you guys or can it be better (i.e: thicker or more "fused")?

Perhaps also I'm just too perfectionist but I saw so much awesome prints made on the UM. :-P Hopefully I can improve my technique and contribute more to the community!

Thanks for any help!

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1) overhangs - you need to get the fan going sooner and keep the heat on the bed below 60C. But above 40C. 40C should be fine. 60C should be fine also. You need zero fan for the bottom layer but you need 100% fan as soon as possible - maybe by .5mm you want 100%. Lots of details on overhangs having this issue here:

I haven't tried it on UM2 yet. There may be a trick to "saving" the changes so I would try changing to huge difference. Try 100mm/sec/sec to make sure you can really see it slowing down at each corner. If that works then try 1000 to 3000mm/sec to reduce ringing.

3) Pillowing

But we can see the interior floor could not bind well to the infill and left holes.

This is called pillowing. Search for it on this forum. This is fixed by adding more fan (do your side 2 fans work?) and also by increasing top/bottom layer thickness.

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Another issue is that "bulge" that appears from the beginning of the notch and for a few layers.

No idea. It doesn't look like a buldge. It could be a faulty Z screw issue but if that's true it will show up on all parts, even the UM robot at the same height. I don't see any bulging on the corners - are you sure it's a buldge? Can you take a better picture?

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Finally, from the bottom, we can see gaps (top part)...is that what's call under extrusion?

Well. Maybe. It looks like the feeder slipped back. But your bottom layer looks underextruded overall. I would say you need to level a little bit tighter with nozzle a tiny bit closer to glass. But I don't know why you got that one little underextruded spot - maybe the filament was tangled? Maybe the nozzle got too cold because the temperature was oscillating? Don't know about this one.

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Thanks for the quick answer! I'll try your tips tomorrow on overhangs, ringing and pillowing. Specially I'll try to adjust the extruder a tad closer. Btw, it there an official and precise distance between the extruder and the plate? I mean, if I use a feeler gage, will I get a more optimal and repeatable adjustment?

For the "bulge" here's a better view:

Hard to explain what is going on, seems not to be a Z problem since it's the only model that has it and just after, I printed the UM robot right after and it show no such problem, still needs move tuning obviously! I'll experiment with temp & speed.

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